A block of mass m is on an inclined plane of angle θ. The coefficient of friction between the block and the plane is μ and tanθ>μ. The block is held stationary by applying a force P parallel to the plane. The direction of force pointing up the plane is taken to be positive. As P is varied from P1=mg(sinθ−μcosθ) to P2=mg(sinθ+μcosθ), the frictional force f versus P graph will look like: